<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>map集合</title>
    <script>

        let user = {
            name: "ldh"
        }
        let map = new Map();

        map.set("age", 20);
        map.set("name", "ldh");


        console.log(map.size)
    </script>
</head>
<body>

</body>
</html>